Motive fluid composition



May 12, 1970 J. P. NORTON L MOTIVE FLUID COMPOSITION Filed 001;. 7, 1968 o o o mwwnwwwwmwww mww4w2wm 010 50 8090 no I30 160170 180190 PRt'SSl/RE (PS/G) I F15. Z

INVENTORS United States Patent Office 3,511,049 Patented May 12, 1970 3,511,049 MOTIVE FLUID COMPOSITION John P. Norton, St. Louis, and Saxon Cole, Shrewsbury, Mo., assignors to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed Oct. 7, 1968, Ser. No. 765,537 Int. Cl. F01k 25/00; C09k 3/00 U.S. Cl. 6036 ABSTRACT OF THE DISCLOSURE A vaporizable-condensible motive fluid composition including selected portions by weight of trichlorotrifluoroethane and trichlorofluoromethane where selected minor portions of a lubricant can be added. The composition freezes at an extremely low temperature and is vaporized in a selected high temperature range to be alternately vaporized and condensed in a closed fluid flow circuit.

BACKGROUND OF THE INVENTION Vaporizable-condensible motive fluids are provided in various closed fluid flow circuits to be alternately vaporized and condensed to furnish power or for other purposes. One such example is a self-powered heating unit where the motive fluid is vaporized to provide a source of power for a turbine, which can drive fan means to move an air stream across a condenser arrangement, where the condenser receives the fluid exhausted from the turbine to heat the air stream to condense the fluid. Since such apparatus is generally provided for low temperature operation it is important that the freezing point of the motive fluid be extremely low to prevent solidification and it is important that the vapor pressure characteristics of the fluid provide the proper operating characteristics for the turbine drive.

SUMMARY OF THE INVENTION The present invention provides a motive fluid composition for use in a self-powered fluid heater which includes a closed fluid flow circuit where the motive fluid is alternately vaporized and condensed to provide power for the turbine and heat to be transferred to the air stream.

Moreover, the present invention provides a motive fluid. composition having an extremely low freezing point and vapor pressure characteristics to assure vaporization of the motive fluid within desired temperature-pressure range for operation of the turbine where significant increase in motive fluid vapor pressure is achieved with relatively small increase in temperature in the operating range.

Various other features of the present invention will become obvious to those skilled in the art upon reading the disclosure set forth hereinafter.

More particularly, the present invention provides a motive fluid composition comprising: thirteen to eighteen percent by weight of trichlorofluoromethane in trichlorotrifluoroethane.

It is to be understood that the compositions and description of one example of the present invention given hereinafter is not by way of limitation and the composition provided by the present invention can be used in various other applications without departing from the scope or spirit of the present invention.

Referring now to the figures which describe the features of the example of the present invention:

FIG. 1 is a schematic illustration of a self-powered air heating apparatus; and,

FIG. 2 is a graph illustrating the vapor pressure-temperature characteristics of one composition in accordance with the present invention.

6 Claims The example of an air heating apparatus as shown in FIG. 1 includes a closed fluid flow circuit including a motive fluid vaporizer 1, which can have a boiler and heat source for example a fuel burning combustor (not shown) to vaporize the motive fluid which is circulated through the circuit to be alternately vaporized and condensed as hereinafter described.

The vaporized motive fluid is emitted from the vaporizer 1 through conduit 2 which communicates with a motive power generator, for example a turbine 3, and the turbine is driven by expansion of the flowing fluid to furnish power for the elements of the heater as hereinafter described.

The expanded motive fluid exhausted from turbine 3 flows through conduit 4 to a condenser 7 where the fluid is condensed and the condensed liquid is emitted through an outlet of condenser 7 to a receiver 8 for recirculation through the system as hereinafter described.

Turbine 3 can be connected to a shaft 6 rotated by the energy expended in expansion of the vaporized motive fluid in turbine 3. As shown, shaft 6 is connected to a transmission 13 to provide power for auxiliary elements of the heater hereinafter described.

A fan 16 is driven by a shaft 14 connected to transmission 13 to move a stream of air to be heated over the surfaces of heat exchange condenser 7 so the stream of air is heated and heat removed from the motive fluid allows condensation of the fluid in condenser 7.

A motive fluid circulating pump 11 is provided to return motive fluid from receiver 8 to vaporizer 1 at a pressure greater than the vaporizer pressure, and is connected to transmission 13 by a shaft 17. Pump 11 is connected to receiver 8 by intake conduit 9 and is connected to the boiler of vaporizer 1 by an outlet conduit 12.

In applications where the vaporizer is heated by a liquid fuel burning combustor, a fuel pump 22, driven by a shaft 18 connected to turbine 3, can be provided to supply fuel from a storage tank 19 to the combustor of vaporizer 1.

The motive fluid composition in accordance with the present invention includes selected amounts by weight of trichlorotrifluoroethane (CCl F--CClF and trichlorofluoromethane (CC1 F).

It has been found that compositions having thirteen to eighteen percent trichlorofluoromethane and eighty-two to eighty-seven percent trichlorotrifluoroethane work satisfactorily in the range of operation normally associated with self-powered fluid heating apparatus of the type hereinbefore described. Furthermore, it has been found that five to seven percent by weight of a suitable mixture of lubricant can be added to compositions in the aforestated range to provide lubrication for the elements of the fluid flow circuit without adversely affecting the operating characteristics of the motive fluid composition.

Referring to FIG. 2 which shows the vapor pressure curve for a mixture of trichlorotrifluoroethane and 15% trichlorofluoromethane which illustrates the features of compositions in the aforementioned composition range it will be noted that the vapor pressure increases slowly with temperature until a temperature of approximately is reached where there is a sudden increase in the rate of increase of vapor pressure with incremental change in temperature. It is recognized that this characteristic is of particular advantage in the use of a motive fluid in accordance with the present invention in a self-powered heater application because in the operating range above 200 F. the rapid increase in pressure with a rather small incremental increase in temperature provides a means to greatly increase the pressure drop across the turbine with a rather small increase in vaporizer temperature. It is further recognized that this characteristic provides means for operating the heater apparatus at relatively low temperature to reduce problems associated with operation of the vaporizer apparatus at extremely high temperatures.

Likewise, the freezing point of compositions provided by the present invention is in the range of -65 F., well below temperatures generally encountered so that the danger that the motive fluid will freeze is minimized.

The invention claimed is:

1. A motive fluid composition to be alternately vaporized and condensed in a closed fluid flow circuit comprising: trichlorotrifluoroethane and thirteen to eighteen percent by weight of trichlorofluoromethane.

2. The composition of claim 1 including five to seven percent by weight of a lubricant miscible in said composition.

3. A motive fluid composition to be alternately vaporized and condensed in a fluid flow circuit comprising fifteen percent trichlorofluoromethane by weight and eight-five percent trichlorotrifluoroethane.

4. The composition of claim 3 including three to five percent by weight of a lubricant miscible in said composition.

5. In a heater system having a closed fluid flow circuit including a vaporizer to vaporize a motive fluid, a turbine to receive vaporized motive fluid to provide power from expansion of said motive fluid through said turbine means, a condenser communicating with the outlet of said turbine to receive expanded motive fluid from said turbine and means to return condensed motive fluid from said condenser to said vaporizer; a motive fluid composition comprising thirteen to fifteen percent trichlorofluoromethane in trichlorotrifluoroethane.

6. The composition of claim 5 including three to five percent of a lubricant miscible in said composition.

References Cited UNITED STATES PATENTS 2,301,404 11/1942 Holmes 60-36 3,282,048 11/1966 Murphy et a1. 60-36 MARTIN P. SCHWADRON, Primary Examiner R. R. BUNEVICH, Assistant Examiner U.S. Cl. X.R. 252--7l 

